Orthopedic impacting device having a launched mass delivering a controlled, repeatable &amp; reversible impacting force

ABSTRACT

A motor-driven orthopedic impacting tool is provided for orthopedic impacting in the hips, knees, shoulders and the like. The tool is capable of holding a broach, chisel, or other end effector, which when gently tapped in a cavity with controlled percussive impacts, can expand the size or volume of an opening of the cavity or facilitate removal of the broach, implant, or other surgical implement from the opening. A stored-energy drive mechanism stores potential energy and then releases it to launch a launched mass or striker to communicate a striking force to an adapter in either a forward or reverse direction. The tool may further include a combination anvil and adapter and an energy adjustment mechanism to adjust the striking force the launched mass delivers to the adapter in accordance with a patient profile.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/795,942 entitled “Orthopedic Impacting Device Having a Launched MassDelivering a Controlled, Repeatable & Reversible Impacting Force” filedFeb. 2, 2020, which is a divisional of U.S. patent application Ser. No.15/439,692 entitled “Orthopedic Impacting Device Having a Launched MassDelivering a Controlled, Repeatable & Reversible Impacting Force” filedFeb. 22, 2017, which claims priority to U.S. Provisional PatentApplication No. 62/381,864 entitled “Electric Motor Driven Tool forOrthopedic Impacting” filed Aug. 31, 2016, which are hereby incorporatedby reference in their entireties.

FIELD

The present disclosure relates to locally powered tools for impacting insurgical applications such as orthopedic procedures, and, moreparticularly, to a hand-held motor driven tool for bidirectional,surgical impacting that is driven by a launched mass to providecontrolled, repeatable impacts to a broach or other end effector.

BACKGROUND

In the field of orthopedics, prosthetic devices, such as artificialjoints, are often implanted or seated in a patient's bone cavity. Thecavity is typically formed during surgery before a prosthesis is seatedor implanted, for example, a physician may remove and or compactexisting bone to form the cavity. The prosthesis usually includes a stemor other protrusion that is inserted into the cavity.

To create the cavity, a physician may use a broach conforming to theshape of the stem of the prosthesis. Solutions known in the art includeproviding a handle with the broach for manual hammering by the physicianduring surgery to impel the broach into the implant area. Unfortunately,this approach is crude and notoriously imprecise, leading to unnecessarymechanical stress on the bone and highly unpredictable depending uponthe skill of a particular physician. Historically, this brute forceapproach will in many cases result in inaccuracies in the location andconfiguration of the cavity. Additionally, the surgeon is required toexpend an unusual amount of physical force and energy to hammer thebroach and to manipulate the bones and prosthesis. Most importantly,this approach carries with it the risk that the physician will causeunnecessary further trauma to the surgical area and damage otherwisehealthy tissue, bone structure and the like.

Another technique for creating the prosthetic cavity is to drive thebroach pneumatically, that is, by compressed air. This approach isdisadvantageous in that it prevents portability of an impacting tool,for instance, because of the presence of a tethering air-line, air beingexhausted from a tool into the sterile operating field and fatigue ofthe physician operating the tool. This approach, as exemplified in U.S.Pat. No. 5,057,112 does not allow for precise control of the impactforce or frequency and instead functions very much like a jackhammerwhen actuated. Again, this lack of any measure of precise control makesaccurate broaching of the cavity more difficult, and leads tounnecessary patient complications and trauma.

A third technique relies on computer-controlled robotic arms forcreating the cavity. While this approach overcomes the fatiguing andaccuracy issues, it suffers from having a very high capital cost andadditionally removes the tactile feedback that a surgeon can get from amanual approach.

A fourth technique relies on the inventor's own, previous work whichuses a linear compressor to compress air on a single stroke basis andthen, after a sufficient pressure is created, to release the air througha valve and onto a striker. This then forces the striker to travel downa guide tube and impact an anvil, which holds the broach and or othersurgical tool. However, this arrangement, due to the pressure of theair, results in the generation of large forces on the gear train andlinear motion converter components, which large forces lead to prematurewear on components.

Consequently, there exists a need for an impacting tool having animproved drive assembly that overcomes the various disadvantages ofexisting systems and previous solutions of the inventor.

SUMMARY

In view of the foregoing disadvantages, an electric motor-drivenorthopedic impacting tool is provided for orthopedic impacting in hips,knees, shoulders and the like. The tool is capable of holding a broach,chisel, or other end effector and gently tapping the broach, chisel orother end effector into the cavity with controlled percussive impacts,resulting in a better fit for the prosthesis or the implant. Further,the control afforded by such an electrically manipulated broach, chisel,or other end effector allows adjustment of the impact settings accordingto a particular bone type or other profile of a patient. The tooladditionally enables proper seating and in the case of bidirectionalmovement the removal of the prosthesis or the implant into or out of animplant cavity and advantageously augments the existing surgeon's skillin guiding the instrument.

In an exemplary embodiment, an electric motor-driven orthopedicimpacting tool comprises a local power source (such as a battery or fuelcell), a motor, a controller, a housing, a method of converting rotarymotion to linear motion (hereafter referred to as a linear motionconverter), a stored-energy drive system or mechanism such as a gas ormechanical spring capable of storing and releasing potential energy, anda striker energized by the stored-energy drive system to be operationalin a forward and/or a rearward direction, where the striker is capableof generating an impact force to a surgical implement. The tool mayfurther deliver focused illumination to the surgery area by way of asemiconductor light source, such as an LED, or traditional incandescentlight source. A handle may be provided for handling the tool by aphysician, or a suitable mount interface for integrating the tool into arobotic assembly. A local power source such as a battery is alsoincluded. As is typical, at least some of the various components arepreferably contained within a housing. The tool is capable of applyingcyclic, repeatable impact forces on a broach, chisel, or other endeffector, or an implant. Given the repeatability of the impact force,finely tuning the impact force to a plurality of levels is alsocontemplated. To this end a plurality of gas springs may be providedtogether with the device in a kit format, whereby different color-codedgas springs may be removably introduced to the tool as needed during asurgical procedure to provide for a range of drive forces.

Regarding the stored-energy drive system, the system is preferablyactuatable by a motor and gearbox in combination with a cam, whichrotates in a first direction compressing a spring, thus storingpotential energy within the stored-energy drive system. The cam furthercontinues to rotate and releases the stored energy, which, in turn, canaccelerate itself or another mass to generate a forward impact force asa drive assembly. As an example, after sufficient displacement of amechanical spring or gas spring, in which stored potential energy isincreased, the cam continues to rotate until it moves past a releasepoint where it ceases to act on the mass, releasing the stored energy.Upon release, the energy or, more preferably, other mass is acceleratedin the forward direction by the stored-energy drive system until itcomes into operative contact with the point of impact, such as the anvilor another impact surface. Conversely, for a bidirectional impactingsystem the cam can alternatively rotate in an opposite, seconddirection, compressing a spring, again storing potential energy withinthe spring storage system. The cam further continues to rotate to arelease point where it ceases to act on the spring storage system andthe spring storage system can release the stored energy, which, in turn,can accelerate itself or another mass to generate a rearward impactforce. As an example, after sufficient displacement of the spring, inwhich stored potential energy of the spring/gas spring is increased, thecam continues to rotate until it moves past a release point where itceases to act on the mass, releasing the stored-energy drive system (ormechanism). Upon release, the stored-energy drive system or other massis accelerated in the opposite, rearward direction by the stored-energydrive system until it comes into operative contact with the point ofimpact, such as the anvil or another impact surface.

In an exemplary embodiment, the launched mass (which can be thestored-energy drive system itself) separates from a pusher plate orpushing surface prior to its point of impact. Accordingly, in thisembodiment, since the entire stored-energy drive system is the launchedmass very high efficiencies were unexpectedly achieved. In a furtherembodiment which uses a mechanical spring, the compression ratio of thespring is less than about 50% of its free length, which the inventor hasfound reduces the likelihood of permanent spring deformation.

In a further exemplary embodiment, the handle may be repositionable orfoldable back to the tool to present an inline tool wherein the surgeonpushes or pulls on the tool co-linearly with the direction of thebroach. This has the advantage of limiting the amount of torque thesurgeon may put on the tool while it is in operation. In a furtherrefinement of the hand grip, there may be an additional hand grip forguiding the surgical instrument and providing increased stability duringthe impacting operation. In a still further embodiment, the tool may beattached to a robot thus eliminating the need for a handle and the toolmay use a tethered or remote power source.

In a further exemplary embodiment, the broach, chisel or other endeffector can be rotated to a number of positions while still maintainingaxial alignment. This facilitates the use of the broach for variousanatomical presentations during surgery.

In a further exemplary embodiment, the tool further comprises a controlelement or controller, which includes an energy adjustment element ormechanism, and which energy adjustment element may control the impactforce of the tool by controlling storage and release of energy outputfrom the stored-energy drive mechanism. The energy may be regulatedelectronically or mechanically. Furthermore, the energy adjustmentelement may be analog or have fixed settings. This control elementallows for the precise control of the impacting operation. The energyadjustment element allows a surgeon to increase or decrease the impactenergy of the tool according to a patient's profile.

In an exemplary embodiment, an anvil of the tool includes at least oneof two points of impact, a forward striking surface or first surface anda rearward striking surface or second surface, and a guide assembly,such as guide rollers, bearings, or Polytetrafluoroethylene (PTFE) orTeflon tracks to constrain the striker to move in a substantially axialdirection. The point of impact of the striker and the resulting force onthe surgical tool can be both in the forward and reverse directions. Inthe bidirectional impacting operation, when a forward force on thesurgical tool is generated, the striker moves along the guide assemblyand continues in the forward direction. A reversing mechanism can beused to change the point of impact of the striker and the resultingforce on the surgical tool. Use of such a reversing mechanism results ina rearward force being exerted on the anvil and/or the broach or othersurgical attachment. As used in this context, “forward direction”connotes movement of the striker toward a broach, chisel or patient, and“rearward direction” connotes movement of the striker away from thebroach, chisel or patient. The selectivity of either bidirectional orunidirectional impacting provides flexibility to a surgeon in eithercutting or compressing material within the implant cavity in that thechoice of material removal or material compaction is often a criticaldecision in a surgical procedure, as discussed, for example, in U.S.Pat. No. 8,602,124. Furthermore, it was discovered in the use of theinventor's own, previous work that the tool could be used in a broaderrange of surgical procedures if the reverse impact force could beapproximately equal to the forward impact force. In an embodiment theforward and rearward forces impact at least two separate and distinctpoints.

In an exemplary embodiment the anvil and the adapter comprise a singleelement, or one may be integral to the other.

In an exemplary embodiment the tool is further capable of regulating thefrequency of the striker's impacting movement. By regulating thefrequency of the striker, the tool may, for example, impart a greatertotal time-weighted percussive impact, while maintaining the same impactmagnitude. This allows for the surgeon to control the cutting speed ofthe broach or chisel. For example, the surgeon may choose cutting at afaster rate (higher frequency impacting) during the bulk of the broachor chisel movement and then slow the cutting rate as the broach orchisel approaches a desired depth. In typical impactors, as shown inU.S. Pat. No. 6,938,705, as used in demolition work, varying the speedvaries the impact force, making it impossible to maintain constant(defined as +/−40%) impact energy in variable speed operation.

In an exemplary embodiment the direction of impacting is controlled by abiasing force placed by a user on the tool and detected by a sensor,such as a positioner sensor, on the anvil. For example, biasing the toolin the forward direction results in the launched mass being launchedforward and gives forward impacting, whereas biasing the tool in therearward direction results in the launched mass being launched rearwardand gives rearward impacting.

In an exemplary embodiment the tool may have a lighting element toilluminate a work area and accurately position the broach, chisel, orother end effector on a desired location on the prosthesis or theimplant.

In an exemplary embodiment a bumper is predisposed between a head of thepiston and an end of the striker, reducing the impact stress andprolonging the life of the entire assembly.

In an exemplary embodiment the tool may also include a feedback systemthat warns the user when a bending or off-line orientation beyond acertain magnitude is detected at a broach, chisel, or other end effectoror implant interface or the orthopedic implement is not advancing.

In an exemplary embodiment the tool may further allow for a replaceablecartridge to vary the impact forces. These cartridges could be rated bythe total energy delivered by the stored energy system when actuated bythe linear motion converter. As an example, a low power cartridge with alimit in the range of 2 to 3 joules or less could be used for soft orosteoporotic bone. In the case of young, hard bone, a power cartridgewith impact energy of 4 to 5 joules could be selected. By allowing for avariety of cartridges, which in an embodiment could be color codedaccording to power, the surgeon would have flexibility in determiningthe impact energy to apply by simply selecting the appropriate powercartridge provided with the tool in a kit.

These together with other aspects of the present disclosure, along withthe various features of novelty that characterize the presentdisclosure, are pointed out with particularity in the claims annexedhereto and form a part of the present disclosure. For a betterunderstanding of the present disclosure, its operating advantages, andthe specific non-limiting objects attained by its uses, reference shouldbe made to the accompanying drawings and detailed description in whichthere are illustrated and described exemplary embodiments of the presentdisclosure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 illustrates a perspective view of an orthopedic impacting tool inaccordance with an exemplary embodiment of the present disclosure inwhich a mechanical spring assembly system is used for generating aforward impact force;

FIG. 2 shows an exemplary embodiment of the tool in FIG. 1 in which thecam positions the piston in the operative position for release for aforward impact;

FIG. 3 shows an exemplary embodiment of the tool in FIG. 1 in whichafter the stored-energy has been released, a launched mass isaccelerated towards a point of impact in a forward direction;

FIG. 4 illustrates a perspective view of an orthopedic impacting tool inaccordance with an exemplary embodiment of the present disclosure inwhich a mechanical spring is used for generating a rearward impactforce;

FIG. 5 shows another perspective view of the impacting tool in FIG. 4from an alternate angle;

FIG. 6 shows an exemplary embodiment of the tool in FIG. 4 in which thecam of the mechanical spring positions piston in the operative positionfor release for a rearward impact;

FIG. 7 shows an exemplary embodiment of the tool in FIG. 4 in whichafter the spring has been released, a launched mass is acceleratedtowards a point of impact in a rearward direction; and

FIG. 8 is an exemplary flow chart illustrating a cyclic operation of theorthopedic impacting tool in accordance with an exemplary embodiment ofthe present disclosure.p

DETAILED DESCRIPTION

A motor-driven orthopedic impacting tool is provided with controlledpercussive impacts. The motor may be electric, such as a brushless,autoclavable motor such as those generally available from Maxon Motor®and/or Portescap®. The tool includes the capability to perform singleand multiple impacts, as well as impacting of variable and varyingdirections, forces, and frequencies. In an embodiment the impact energyis adjustable. In another embodiment the impact is transferred to abroach, chisel, or other end effector connected to the tool.

The tool further includes a housing. The housing may securely cover andhold at least one component of the tool and is formed of a materialsuitable for surgical applications, such as aluminum orPolyphenylsulfone (PPSF or PPSU), also known as Radel®. In anembodiment, the housing contains a motor, at least one reducing gear, alinear motion converter, a spring element which is preferably amechanical or gas spring, a striker or launched mass, a control circuitor module, an anvil, a first or forward striking surface for forwardimpact, and a different, second or rearward striking surface forrearward impact.

The tool further may include a handle portion with an optional hand gripfor comfortable and secure holding of the tool, or a suitable mountinterface for integrating the tool into a robotic assembly while in use,and an adapter, a battery, a positional sensor, a directional sensor,and a torsional sensor. The tool may further deliver focusedillumination by way of a semiconductor light source, such as an LED, ortraditional incandescent light source to provide light in the surgicalwork area in which a surgeon employs the tool. The anvil may be coupledto a broach, chisel or other end effector known in the art through theuse of an interfacing adapter, which adapter may have a quick connectmechanism to facilitate rapid change of different broaching sizes. Theanvil may further include a locking rotational feature to allow the toolto be positioned in different fashions as to gain tissue clearance totool features such as the handle.

Referring now generally to FIGS. 1 through 7 , in an exemplaryembodiment, a bidirectional impact force may be generated using a dualmechanical spring assembly system, as illustrated, for example, in FIG.1 . Alternatively, a single mechanical spring assembly may be used. FIG.1 shows a perspective view of an orthopedic impacting tool in accordancewith an embodiment of the present disclosure in which a motor andgearbox 8 of the mechanical spring assembly system, in combination witha linear motion converter, which includes a cam 12 and a cam follower13, actuates a first spring piston 19 a (hereinafter referred to as the“first piston 19 a”) and/or a launched mass or striker 15, in order toultimately generate a forward impact force. It is to be noted that thepiston generally refers to a thrusting or push off element and can haveany of a number of shapes. The cam 12 is shown as having a symmetricalprofile, a dual wedge shape, but the design contemplates that any shapemay be used which provides a quick release of the spring. Alternativeways for actuating and quickly releasing the spring include, but are notlimited to, using an interrupted rack and pinion or a climbingmechanism. The spring assembly system further includes, among othercomponents, reducing gears 7 and an anvil 5. The first piston 19 aengages a first spring 2 a, which can be either a mechanical or gasspring. In the mechanical spring assembly system, the deflection inrelation to a free length of the spring is preferably less than 50%.Music wire or, more preferably, stainless steel or titanium are suitablematerials for the spring. Preferably, the spring is a compressionspring, although other types of springs are contemplated. In the gasspring assembly system, the gas spring operates under pressure in arange of about 100 to 3000 psi, for example. The gas spring ispreferably initially charged with a non-oxidizing gas, such as nitrogen,or an inert gas, such as argon. One of the advantages of using nitrogencan include a lower permeation rate through seals of the gas spring,resulting in a potentially longer shelf life for the seals and thespring itself.

FIG. 2 is an exemplary embodiment of the tool in FIG. 1 in which the cam12 used for actuating the first piston 19 a has the first piston 19 a“cocked” in the operative position ready for release, or stated anotherway, the motor 8 rotates the cam 12 in a first direction (viewed ascounterclockwise for tautological purposes), as shown by arrow 42 a, andcompresses the first piston 19 a against a first pusher plate 26 a, thusstoring potential energy within the first spring 2 a. In the “cockingphase” the first piston 19 a, in combination with the launched mass orstriker 15, contacts and is pushed by the cam follower 13, which isdriven by the cam 12 in the first direction. As the cam 12 continues torotate in the first direction, energy stored inside the first spring 2 aincreases until the cam 12 moves past a release point where it ceases toact on the striker 15 (see FIG. 3 , for example). The striker (orlaunched mass) 15 is now free to travel under the stored potentialenergy of the first spring 2 a. In particular, after a sufficientdisplacement of the first piston 19 a, and after the cam 12 releases thefirst piston 19 a and/or the launched mass 15 combination, the firstpiston 19 a moves in a forward direction, i.e., a direction toward thepoint of impact, and, at the same time, accelerates the launched mass orstriker 15, which is in contact with the face of the first piston 19 a.As shown, for example, in FIG. 3 , the first piston 19 a releases fromthe striker 15, launching it towards the anvil 5. It was unexpectedlydiscovered in this invention that the release of the striker 15 from thepusher plate 26 a, which essentially creates a portion of free flightduring its travel, dramatically reduces the recoil generated andexperienced by the surgeons' hands, resulting in a more controllabletool. The striker 15, which has been launched towards the end of thetool that is proximate to the end effector or patient, then percussivelyimpacts a first surface or forward striking surface of the anvil 5,where a maximum displacement of the anvil is less than 10 mm. The impactof the striker 15 on the anvil 5 communicates a forward impact force toan adapter (not shown) and thereby to the broach, chisel, or otherorthopedic instrument. The launched mass or striker 15 may beconstructed from a suitable material such as steel or any other materialhaving similar properties, lending it to repeated impacting. In anembodiment, a ratio of a weight or mass of the launched mass or striker15 to a weight or mass of the tool is preferably less than 25%, and thelaunched mass 15 has an amount of free flight before contact, bothfactors contributing to a further reduction in the recoil generated.

In a further embodiment it was unexpectedly discovered by increasing theweight or mass of the launched mass in relation to the weight or mass ofthe anvil that the impact energy was more effectively transferred to thesurgical implement. For example, when a ratio of the mass of thelaunched mass to the mass of the anvil is less than 25%, the resultanttransfer efficiency is extremely low, i.e., less than 50% for a typicalcoefficient of restitution of 0.8. As such, it was found that massratios under 50% resulted in the lowest transfer efficiencies of theimpact.

In a further embodiment, as illustrated in FIG. 2 , for example, as thestriker 15 moves in the rearward direction, towards the pusher plate 26a, a bumper 14 a functions as a stopper to prevent an end face of thepiston 19 a from impacting the striker 15. The bumper 14 a absorbs theimpact of the piston 19 a immediately before the launched mass orstriker 15 is launched in the forward direction. It was discovered inthe course of the invention that without having the piston 19 a come torest on the bumper 14 a, excessive wear occurred resulting in failure ofthe piston 19 a. Accordingly, such bumper 14 a prevents damage to thespring assembly system, particularly the piston 19 a, during repeatedoperation. The bumper 14 a can be one of a plastic or more preferably arubber or urethane material.

As discussed above, it has been determined by the inventor that hisprevious designs occasionally resulted in the surgical implement seizingin a biological cavity and the impact of the striker 15 in the rearwarddirection may be insufficient to dislodge the tool. Further, it wasdiscovered that the rearward force needs to be communicated as a sharpretracting impact in order to dislodge the surgical implement.Accordingly, in the present bidirectional impacting system, there are atleast two different impacting surfaces, and, when the tool is beingpulled away from the cavity, the striker 15 will impact an alternatesurface on the anvil 5 and thereby communicate a rearward force on theanvil 5.

FIGS. 4-7 , for example, illustrate a perspective view of an orthopedicimpacting tool in accordance with an embodiment of the presentdisclosure in which the motor and gearbox 8 of the mechanical springassembly system rotates the cam 12 in a second direction (viewed asclockwise for tautological purposes), as shown by arrow 42 b, andlaunches the mass or striker 15, in order to ultimately generate arearward impact force. FIG. 4 , and similarly FIG. 5 , which is anotherperspective view of the impacting tool shown in FIG. 4 from an alternateangle, illustrates the cam 12 in mid-rotation. As the motor 8 continuesto rotate the cam 12 in the second direction, a second spring piston 19b (hereinafter referred to as the “second piston 19 b”) engages a secondspring 2 b and is compressed against a second pusher plate 26 b, thusstoring potential energy within the second spring 2 b. The second piston19 b, in turn, is “cocked” in the operative position ready for release(see FIG. 6 ). In the “cocking phase” the second piston 19 b, incombination with the launched mass or striker 15, contacts and is pushedby the cam follower 13. As shown in FIGS. 6 and 7 , for example, an endsurface of the striker or launched mass 15 includes a pair of extensionsor protrusions 32 integral with the launched mass 15 or provided asseparate elements bolted to the launch mass 15. As the cam 12 continuesto rotate in the second direction, energy stored inside the secondspring 2 b increases until the cam 12 moves past a release point whereit ceases to act on the striker 15 (see FIG. 7 , for example).

The striker or launched mass 15 is now free to travel under the storedpotential energy of the second spring 2 b. In particular, after asufficient displacement of the second piston 19 b, and after the cam 12releases the second piston 19 b and/or the launched mass 15 combination,the second piston 19 b moves in a rearward direction, i.e., a directiontoward the point of impact, and, at the same time, accelerates thelaunched mass or striker 15, which is in contact with the face of thesecond piston 19 b. As shown, for example, in FIG. 7 , the second spring2 b releases from the striker 15, launching it away from the end of thetool that is proximate to the end effector or patient, with theextensions or protrusions 32 of the launched mass 15 impacting analternate, second or rearward striking surface of the anvil 5, therebypercussively imparting a rearward impact force on the anvil 5, where amaximum displacement of the anvil is less than 10 mm.

Similar to the spring bumper 14 a illustrated in FIG. 2 and discussedabove, a spring bumper 14 b shown in FIG. 4 also functions as a stopperto prevent an end face of the piston 19 b from impacting the striker 15,as the piston 19 b moves in the forward direction. The bumper 14 babsorbs the impact of the piston 19 b immediately before the launchedmass or striker 15 is launched in the rearward direction. As discussedabove, it was discovered in the course of the invention that withouthaving the piston 19 b come to rest on the bumper 14 b, excessive wearoccurred resulting in failure of the piston 19 b. Accordingly, suchbumper 14 b prevents damage to the spring assembly system, particularlythe piston 19 b, during repeated operation. Similar to bumper 14 a, thebumper 14 b can be one of a plastic or more preferably a rubber orurethane material.

In an exemplary embodiment, a direction of the force on the anvil 5 iscontrolled by the user's (such as a surgeon's) manual force on the tooldetected by a sensor 28, which can be a positional sensor, on the anvil5. For example, biasing the tool in the forward direction results in thelaunched mass or striker 15 being launched forward and gives forwardimpacting, whereas biasing the tool in the rearward direction results inthe striker 15 being launched rearward and gives rearward impacting.

In an embodiment, as the cam 12 assembly completes its stroke, itpreferably activates a sensor 22, as shown, for example, in FIG. 5 ,coupled operatively to a controller 21. The sensor 22 assists in theregulation of the preferred cyclic operation of the cam 12. For example,the sensor 22 may signal the motor 8 to stop such that the cam 12 is ator near a point of minimal potential energy storage. Thus, in onecomplete cycle, a forward or a rearward impacting force may be appliedon the broach, chisel, or other end effector, or on the implant orprosthesis. In a further embodiment, it may be advantageous to stop thecam 12 near a point of maximum potential energy storage to reduce alatency in the surgeons' hands. Latency, as defined, is the time betweenwhen the surgeon (or user) activates the orthopedic impacting tool andthe tool actually delivers an impact. It has been determined by theinventor that latencies of around 100 milliseconds or less appearessentially as an instantaneous response. By stopping the cam 12 at apoint where at least part of the potential energy has been stored, thetool has the effect of near instantaneous release of the potentialenergy upon actuation of a tool trigger 30. Alternatively, or inaddition, a second sensor (not shown) may detect that the broach hasstopped advancing for a period of less than 10 seconds, or morepreferably, less than 3 seconds during operation, and stops the toolfrom further impacting. A surgeon will then have to re-initiate thecycle to continue operation.

FIG. 8 is an exemplary flow chart illustrating a cyclic operation of anorthopedic impacting tool according to an exemplary embodiment of thepresent disclosure. At the start of a cycle, a trigger is pressed instep 800 and it is first determined in step 802 whether the orthopedicimpacting tool is charged and ready for use. If a voltage of a localpower source, such as a battery, is less than a threshold minimum, thenthe battery is set to charge in step 804. If the voltage of the batteryis greater than the threshold minimum, then it is next determined instep 806 whether an anvil and/or broach or other surgical attachment iscorrectly positioned relative to a cavity of the patient's bone. If theanvil and/or the broach or other surgical attachment is correctlypositioned, the operation moves on to step 810; otherwise, the systemwaits until the position is corrected in step 808. Next, in step 810, itis determined whether a decision has been made as to which direction torotate the motor and gearbox based on whether the tool is being used togenerate a forward impact force or a rearward impact force. If therotation direction has been decided, then the motor and gearboxcombination starts rotating in step 814 in order to complete an impactcycle; otherwise, the system waits until the rotation direction has beendetermined in step 812. Once the motor gearbox completes an impactcycle, step 816 determines whether a cam sensor has been activated. Ifthe sensor has been activated, then the process proceeds to step 818 todetermine whether the trigger is still maintained; otherwise, theprocess returns to step 814 to allow the motor to continue rotatinguntil the cam sensor has been activated. If a trigger is maintained instep 818, then the operation cycles back to step 814 where the motorcontinues to rotate, causing the tool to continue generating impacts;otherwise, the operation of the orthopedic impacting tool ceases at step820.

The controller 21 preferably operates with firmware implementing thecyclic operation described in FIG. 8 , which results in the orthopedicimpacting tool being able to generate a repeatable, controllableimpacting force. The controller 21 can include, for example, intelligenthardware devices, e.g., any data processor, microcontroller or FPGAdevice, such as those made by Intel® Corporation (Santa Clara, CA) orAMD® (Sunnyvale, CA). Other type of controllers can also be utilized, asrecognized by those skilled in the art.

Advantageously, the dual piston and spring assembly system does not needor use a detent or a magnet for generating a higher energy impact. Theimpact energy output from the stored-energy drive system is between 1 to10 joules. In the present bidirectional impacting system the dual pistonand spring assembly mechanism is approximately 80% efficient in therearward direction compared to prior designs, which were about 20%efficient, and more preferably at least 60% efficient. For example, inprevious designs, the forward impact force generated approximately 3.5 Jof energy, whereas the rearward impact force generated 0.4 J of energy,resulting in a loss of nearly 80% of the energy.

Further, it was unexpectedly discovered that by keeping the compressionratio of the spring to less than 50% of its free length, and morepreferably less than 30%, that spring life and impact consistency weremaximized. One unexpected effect was generating much more consistentimpacts between the striker 15 and the anvil 5, which was a result ofthe spring not permanently deforming. Indeed, the consistency of theimpacts, as generated by the gas or mechanical spring, was found to bewithin +/−10% of the nominal design value since the impact energy wasnot subject to atmospheric pressure variations, as it was in theinventor's prior inventions.

The tool may further facilitate controlled continuous impacting, whichimpacting is dependent on a position of the trigger switch 30operatively coupled to the power source or motor, for example. For suchcontinuous impacting, after the trigger switch is activated, anddepending on the position of the trigger switch 30, the tool may gothrough complete cycles at a rate proportional to the position of thetrigger switch, for example. Thus, in either the single impact orcontinuous impacting operational modes, the creation or shaping of thesurgical area is easily controlled by the surgeon.

As discussed previously, the tool is capable of varying the amount ofimpact energy per cycle by way of, for example, choosing an appropriateinternal pressure for a replaceable gas spring cartridge or a differentgauge spring for the stored-energy drive system. A gas spring cartridgepreferably has an internal pressure of 100 psi, more preferably, between300 and 3000 psi. Further, the gas spring cartridge may have a pressurerelease mechanism which releases the pressure at any temperature above100° C. It will be appreciated that since the drive mechanism forimparting potential energy into the gas spring is a fixed stroke,different impact energies can be obtained in any given surgery by simplyusing a gas spring cartridge with a different pressure. In a furtherembodiment, an element, such as a linear cam, can be used to vary theamount of compression in the stored-energy drive system by changing alocation of the pusher plate, for example. By controlling the impactenergy the tool can avoid damage caused by uncontrolled impacts orimpacts of excessive energy.

In another embodiment, replaceable gas spring cartridges arepresterilized and delivered to a surgeon in a sealed container, such asa bag. This allows the surgeon to identify any gas spring cartridgesthat are leaking, as the bag may be inflated due to the leaking gas.

In a further embodiment, the tool may further be designed to facilitateextraction of well-fixed implants or “potted” broaches. Such embodimentrotates the cam 12 in the second, clockwise direction 42 b and launchesthe mass or striker 15 such that the movement of the striker 15 is awayfrom the patient, causing a retraction or rearward force on the anvil 5.

The tool may further include a compliance element (not shown) insertedbetween the striker 15 and the anvil 5. Preferably, the complianceelement is a resilient material that recovers well from impact andimparts minimal damping on the total energy. As an example, a urethanecomponent could be inserted at the interface where the striker 15impacts the anvil 5. In a further embodiment, the compliance element maybe inserted in such a fashion that it only reduces the impact force inthe forward direction and does not affect the desire for a sharp impactforce in the rearward direction. This type of compliance element canlimit the peak force during impact to preclude such peaks from causingfractures in the patient's bone, yet maintain the high peak forcenecessary to be able to retract stuck broaches or other surgicalimplements.

In a still further embodiment, it is understood that the impactor couldbe coupled to a robot, for example, thus potentially eliminating theneed for a portable power source (battery) and or hand grip on the tool.

In a further embodiment, the coupling of the adapter (not shown) to thetool may comprise a linkage arrangement or other adjustment mechanismsknown in the art such that the position of the broach, chisel or otherend effector can be modified without requiring the surgeon to rotate thetool. The orthopedic tool disclosed herein provides various advantagesover the prior art. It facilitates controlled impacting at a surgicalsite, which minimizes unnecessary damage to a patient's body and allowsprecise shaping of an implant or prosthesis seat. The tool also allowsthe surgeon to modulate the direction, force, and frequency of theimpacts, which improves the surgeon's ability to manipulate and controlthe tool. For example, the orthopedic tool can be used solely forretraction purposes depending on the surgical procedure being performed.Similarly, the tool can be customized to have different forward andreverse impact forces. In a mechanical spring assembly system, forexample, different gauge springs can be used for forward and reverseimpact. The force and compliance control adjustments of the impactsettings allow a surgeon to set the force of impact according to aparticular bone type or other profile parameter of a patient. Further,the improved efficiency and reduced linear motion converter loads allowuse of smaller batteries and lower cost components. The tool therebyenables proper seating or removal of the prosthesis or implant into orout of an implant cavity. Further, the piston and spring assemblyprovides a simple means for adjusting the impact energy for a particularsurgery. Additionally, since the spring assembly is essentially governedby the mechanical properties of the spring, such as the deflection,preload and spring constants, the resulting tool imparts a predictableimpact energy independent of the operational speed. Furthermore, in oneembodiment in which the gas spring cartridge is replaceable, elementssubject to high wear, such as seals and pistons, can be replaced in eachsurgery, resulting in a more robust, long life tool and reducing pointsof failure.

The foregoing descriptions of specific embodiments of the presentdisclosure have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit thepresent disclosure to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The exemplary embodiment was chosen and described in order tobest explain the principles of the present disclosure and its practicalapplication, to thereby enable others skilled in the art to best utilizethe disclosure and various embodiments with various modifications as aresuited to the particular use contemplated.

What is claimed is:
 1. A surgical impacting tool, comprising: astored-energy drive mechanism configured to produce a spring-drivenstriking force; a controller configured to control storage and releaseof energy output from the stored-energy drive mechanism; an anvilcoupled to a surgical implement; and a launched mass, responsive to thestored-energy drive mechanism, to communicate the striking force to theanvil to urge the surgical implement in a first direction.
 2. A kit forinserting or extracting a tool lodged within a biological object, thekit comprising: a surgical impacting tool including: a stored-energydrive mechanism configured to produce a spring-driven striking force, acontroller configured to control storage and release of energy outputfrom the stored-energy drive mechanism, an adapter configured to receivea surgical implement, and a launched mass, responsive to thestored-energy drive mechanism, to communicate the striking force to theadapter to urge the surgical implement in a first direction; and aspring cartridge usable in the surgical impacting tool, the cartridgeused to deliver the striking force to the adapter.
 3. The kit of claim2, wherein the spring cartridge is selected from a plurality ofcolor-coded spring cartridges, each color corresponding to a differentstriking force.
 4. The kit of claim 2, wherein the spring cartridge ispackaged as a replaceable cartridge.
 5. The kit of claim 2, wherein thespring is one of a mechanical, gas, or elastomeric spring.
 6. Thesurgical impacting tool of claim 1, wherein the anvil has a first impactsurface and a different second impact surface, and wherein the launchedmass is operable to impact the first impact surface for generating aforward impact force and the second impact surface for generating arearward impact force.
 7. The surgical impacting tool of claim 1,wherein the stored-energy drive mechanism includes a spring which is oneof a mechanical, gas, or elastomeric spring.
 8. The surgical impactingtool of claim 1, wherein a ratio of a mass of the launched mass to amass of the anvil is at least 50%.
 9. The surgical impacting tool ofclaim 6, wherein a direction of impacting is controlled by a biasingforce applied to the tool, wherein the biasing force in a directiontoward a biological object causes the launched mass to impact the firstimpact surface, and wherein the biasing force in a direction away fromthe biological object causes the launched mass to impact the secondimpact surface.
 10. The surgical impacting tool of claim 1, wherein aratio of a mass of the launched mass to a mass of the tool is less than25%.
 11. The surgical impacting tool of claim 1, wherein a maximumdisplacement of the anvil is less than 10 mm.
 12. The surgical impactingtool of claim 1, wherein the energy output from the stored-energy drivemechanism is less than 8 joules.
 13. The surgical impacting tool ofclaim 6, wherein an impact of the rearward impact force is at least 60%of the forward impact force.
 14. The surgical impacting tool of claim 1,wherein the release of the energy from the stored-energy drive mechanismresults in unconstrained displacement of the launched mass beforecommunicating the striking force to the anvil.
 15. The surgicalimpacting tool of claim 7, wherein the mechanical spring is made of atleast one of stainless steel and titanium.